[The world is ageing: a pact of social solidarity is an imperative].

Abstract This text presents the key topics, which guided the discussions about demographic change and the resultant public health implications. With the ageing of the societies, the health problems of the elderly put pressure on health and social security systems. With regard to work and social wellbeing, there are three important sub-topics: the labor market and the elderly; social security and questions related to shelter for the aged population. The ageing process normally occurs in good health conditions unless there is disease. In addition, the scientific and technological achievements in the health area allow for a better quality of life for the elderly. This is why preventive strategies over the lifespan turned more important for meeting today's challenges and increasingly those of tomorrow. As refers to innovation and markets, longevity creates numberless opportunities especially in terms of new products and markets. On the other hand, the term "productive ageing" has been widely used for defining the increasing trend towards a life style in an ageing society. Finally we will approach the topic ageing and development showing that the demographic shift is already one of the most urgent global problems, being addressed by public policies both in the developed and developing countries.